/Engine/Source/Runtime/Engine/Classes/Engine/Polys.h
Return whether this poly and Test are facing each other. The polys are facing if they are noncoplanar, one or more of Test's points is in front of this poly, and one or more of this poly's points are behind Test.
int32 Faces ( const [FPoly](API\Runtime\Engine\Engine\FPoly) & Test ) const